Photographic silver halide elements containing anti-bronzing agents



United. States Patent 3,282,696 PHGTOGRAPEHC SILVER HALIDE ELEMENTS CONTAINING ANTI-BRONZING AGENTS Jozef Frans Willems, Hendrik Adolf Pattijn, and Gerard Michiel Sevens, Wilrijk-Antwerp, Belgium, assignors to Gevaert Photo-Producten N.V., Mortsel-Antwerp, Belgium, a Belgian company No Drawing. Filed Jan. 7, 1963, Ser. No. 249,595 Claims priority, application Belgium, Jan. 5, 1962,

41,269, Patent 612,311

8 Claims. (Cl. 96-67) This invention relates to a method -for obtaining photographic images which are protected aaginst bronzing caused by hot glazing or mechanical drying.

The images obtained in light-sensitive silver halide emulsion layers often undergo changes during processing among others during hot glazing or mechanical drying at high temperature. During these treatments loss of density occurs easily by the so-called bronzing ofthe silver image.

It is known to add small amounts of chemical compounds to light-sensitive materials containing silver halide or to certain processing baths in order to avoid decrease of density as a result of high glossing.

In addition to the fact that these compounds do not completely counteract bronzing, they still show other disadvantages when b'eing added to a silver halide emul- The most important disadvantage is their mostly very strong desensitizling action.

It has now been found that !by adding compounds according to the following general formula:

wherein:

R represents an aryl group or a substituted arryl group,

R represents .a bivalent group such as an alkylene group,

X represents an oxygen atom or an imide group, and

X represents a hydrogen atom, an alkaline metal atom,

an ammonium group or a silver atom,

to the light-sensitive silver halide emulsion layer and/ or to at least one water-permeable layer of the light-sensitive material at the same side of the support as said emulsion layer and/or by dissolving such compounds in at least one of the photographic baths, the disadvantages caused by hot glazing or mechanical drying are prevented.

The compounds according to the present invention can be used in their free mercapto form as well as in the form of their alkaline metal salts, their ammonium salts or their colloidal silver salts.

The light-sensitive silver halide emulsion wherein compounds according to the present invention can be incorporated can be any silver halide emulsion such as 'a g'elatino-silver chloride emulsion, a gelatino-silver chlorobromide emulsion, a gelatino-silver chloroiodide emulsion, a gelatino-silver bromide emulsion, a gelatino-silver bromoiodide emulsion, and a gelatino-silver chlorobromoiodide emulsion. The emulsion can be sensitized chemically as we'll as optically. It may moveover contain all known additives such as anti-fogging agents, stabilizers, hardening agents, softening agents and dispersing agents.

The compounds according to the present invention can be added during any stage of the preparation of the emulsion, e.g. during the formation of the silver halide or durration is given or reference is made to.

Patented Nov. 1, 19 66 "ice ing the physical or chemical ripening, but preferably after the chemical ripening.

The amount, in which the compounds according to the present invention may be added depends on the emulsion used but it generally varies from 0.15 to 9.0 g. (preferably from 0.25 to 4.7 g.) per mol of silver halide when using the free mercapto compounds, their alkaline metal salts or their ammonium salts, and from 0.3 g. to 18 g. (preferably fr-om 0.5 g. to 10 g.) per mol of silver halide when using their silver salts as a colloidal dispersion in gelatin or in another protective colloid.

When using the silver salts of the compounds according to the present invention there is no loss in sensitivity or contrast of the photographic material, whereas the use of the compounds in their free mercapto form or as alkaline metal or ammonium salt can sometimes cause a little loss in sensitivity and irregular fog. However, this can be easily counteracted by incorponating a little of p toluene sulfini'c acid into the photographic material, preferably in one of the water-permeable layers, in a concentration mostly varying from 1 to 5 g. per 15 sq. m.

It is also prossible to incorporate the compounds according to the present invention into a hydrophilic layer adjacent to the light-sensitive layer e.g. in the covering layer or in another layer from which, during fixation, they can diffuse to the silver halide emulsion layer in their free mercapto form.

The amount in which the compounds according to the present invention are added to the covering layer or auxiliary water-permeable layers mostly varies from 5 to mg./ sq. m. when using them in their free mercapto form or in the form of their alkaline metal salts or ammonium salts and from 10 to 350 rug/sq. In. when using them in the form of their silver salts.

The compounds according to the present invention, may also be dissolved in a processing bath such as a fixing bath or a separate processing bath e.g. just be- :fore hot glazing or mechanical drying. This bath may eventually be a bath containing surface active substances. The concentration in which the compounds according to the present invention are dissolved in such baths varies mostly from 0.5 g. to 2.5 g. per liter of bath.

The following are compounds according to the present invention, and of each compound a method of prepa- The preparations given below relate to the compounds in their (free mercapto form, from which, if necessary, the salts can easily be prepared. After these preparations, examples are given which illustrate the anti-bronzing properties of photographic materials according to this invention.

Preparation 1 The preparation of N-phenyl-2'-mercaptoethyl carbamate is described by .T. F. Smith and E. C. Friedrich in J. Am. Chem. Soc. 81 (1959) 161.

Preparation 2 3 The preparation of N-1-naphthyl-2'-mercaptoethyl carbamate is also described by J. F. Smith and E. C. Friedrich in J. Am. Chem. Soc. 81, (1959) 1961.

Preparation 3 N-2-naphthyl-2'-mercaptoethyl carbamate is prepared as follows:

In a three-necked flask of 500 cm. fitted with a stirrer, a thermometer, a dropping funnel and a condenser with calcium chloride tube, 33.8 g. of B-naphthyl isocyanate are dissolved by heating in 150 cm. of anhydrous benzene. The solution is cooled till 40 C. To this solution a solution of 17.2 g. of fl-mercaptoethanol in 50 cm. of anhydrous benzene is dropwise added, whereupon the whole is heated at boiling temperature for 90 min. After 24 h. the formed precipitate is sucked off and the filtrate is concentrated. The sucked 01f precipitate and the residue of concentrating are extracted with naphtha in a Soxhlet apparatus between 90 and 120 C.

After cooling and sucking oil 16 g. of solid reaction product are obtained. Melting point: 88 C.

Preparation 4 N-phenyl-N'-2-mercapto-ethylurea is prepared as follows:

' In a three-necked flask of 500 cm. fitted with a stirrer, a thermometer, a dropping funnel and a condenser with a calcium chloride tube, 8.5 g. of fi-mercapto-ethylamine are dissolved in 350 cm. of anhydrous benzene. The solution is cooled till about 45 C., whereupon a solution of 11.9 g. of phenyl isocyanate in 50 cm. of anhydrous benzene is dropwise added, whereby the temperature is kept at about 50 C. The solution immediately becomes turbid and a precipitate is formed. The reaction mass is allowed to digest on a boiling water bath for still 2 h. After cooling, sucking off and recrystallizing from ethanol, 9.5 g. of solid product are obtained. Melting point: 193 C.

Preparation 5 N-1-naphthyl-N'-2-mercapto ethylurea is prepared as follows:

In a three-necked flask of 500 cm. fitted with a stirrer, a thermometer, a dropping funnel and a condenser with a calcium chloride tube, 8.5 g. of ,B-mercaptoethylamine are dissolved in 300 cm. of anhydrous benzene. The solution is cooled till about 35 C. and a solution of 16.9 g. of a-naphthyl-isocyanate in 50 cm. of anhydrous benzene is dropwise added, the temperature being kept at about 40 C. A white precipitate is immediately obtained, which is allowed to digest for 2 h. on a boiling water bath. After cooling and sucking off, the precipitate is recrystallized from acetonitrile yielding 20 g. of product. Melting point: 168 C. r

The following examples illustrate the present invention.

Example 1.An ammoniacal gelatino-silver bromoiodide emulsion of average gradation, containing 3.5

i this light-sensitive emulsion layer is coated with a gelatincontaining covering layer. The material is exposed under a sensitometric step-wedge and after development, fixation and rinsing, it is hot-glazed by pressing the imageside against a heated polished metal surface. The reflection density is measured by means of a MacBeth densitometer before and after being subjected to high glossing. The following result is obtained.

Maximum density Before After being being subjected subjected to high to high glossing glossing Comparison material (containing no antibronzing agent according to this invention) 2.13 1. 80 A material such as the comparison material,

but comprising per sq. m. 15 mg. of the compound according to preparation 1 2.10 2.03 A material such as the comparison material,

but comprising per sq. m. 15 mg. of the compound according to preparation 2 2.08 2. 08 A material such as the comparison material,

but comprising per sq. m. 15 mg. of the compound according to preparation 3 2. 15 2.06 A material such as the comparison material, but into which per sq. m. 27 mg. of the colloidal silver salt of the compound according to preparation 1 are incorporated in the form of a dispersion 2.12 2.11

Example 2.An ammoniacal gelatino-silver bromoiodide emulsion of average gradation, containing 3.0 mol percent of silver iodide based on the total amount of silver halide and to which products according to the invention have been added, is applied on a baryta-coated paper supportv in such a Way, that the emulsion layer comprises per sq. m. an amount of silver halide equivalent to 2.5 g. of silver nitrate.

After treating this material in the same way as the material of Example 1, the following results are obtained:

Maximum density Before After being being subjected subjected to high to high giossing glossing Comparison material (containing no antibronzing agent according to this invention) 1. 1. 75 A material such as the comparison material,

but into which per sq. m. 20 mg. of the colloidal silver salt of the compound according to preparation 5 are incorporated in the form of a dispersion 1.93 1.87 A material such as the comparison material,

but into which per sq. m. 20 mg. of the colloidal silver salt of the compound according to preparation 3 are incorporated in the form of a dispersion 1. 93 1. 97

Example 3.An ammoniacal gelatino-silver bromoiodide emulsion of hard gradation, containing 1.0 mol percent of silver iodide based on the total amount of silver halide, and to which products according to the invention have been added, is applied on a baryta-coated paper support in such a way, that the emulsion layer comprises per sq. m. an amount of silver halide equivalent to 2.8 g. of silver nitrate. After treating the material in the same way as the material of Example 1, the following results are obtained:

Maximum density Before After being being subjected subjected to high to high glossing glossing Comparison material (containing no antibronzing agent according to this invention) 2. 11 1. 82 A material such as the comparison material,

but containing per sq. m. mg. of the compound actording to preparation 5 or of its sodium salt 2. 13 1. 94 Comparison material (containing no antibronzing agent according to this invention) 2. ll 1. 78 A material such as the comparison material,

but containing per sq. m. 10 mg. of the compound according to preparation 1 or of its sodium salt 2. 10 2. O3

material such as the comparison material, but containing per sq. m. 10 mg. of the compound according to preparation 3 or of its sodium salt 2. 10 1. 98 Comparison material (containing no antibronzing agent according to this invention) 2. 17 1. 87 A material such as the comparison material,

but into which per sq. m. 17 mg. of the colloidal silver salt of the compound according to preparation 1 are incorporated in the iorm of a dispersion 2. 14 2. 01 A material such as the comparison material,

but in which per sq. m. 17 mg. of the colloidal silver salt of the compound according to preparation 3 are incorporated in the form of a dispersion 2. 19 1. 97

Example 4.A light-sensitive material as described in Example 1, but containing no products according to this invention, is exposed, developed and treated in a fixing bath, containing per litre 1 g. of the product according to preparation 1. The following results are obtained:

Example 5.A gelatino-Silver chloroiodide emulsion containing 1.5 mol percent of silveriodide based on the total amount of silver halide, to which the usual coating compositions have been added, is applied on a barytacoated paper support. After drying, this material is exposed under a step-Wedge, developed, fixed and rinsed. The material thus processed is subjected to high glossing by pressing the image-side against a heated polished metal surface. A strong bronzing of the silver image arises especially in the highlight areas. However, when starting from a same emulsion to which per 12 g. of silver, an alcoholic solution of 385 mg. of the product according to preparatiorrl is added before coating, only a very little decrease in density arises after being subjected to high glossing. The maximum density of these two materials is measured by means of a MacBeth densitometer. The results are listed below.

graphic material keeps its density after high glossing.

Example 7 .An orthochromatic gelatino-silver chloroiodide emulsion for document reproduction purposes, containing 0.6 mol percent of silver iodide based on the total amount of silver halide and having been prepared from 45 g. of silver nitrate per kg. of emulsion, is applied on a baryta-coated paper support of 90 g./sq. m. A strip of this material is exposed under a step-wedge. After being developed, fixed and rinsed, this strip is mechanically dried by pressing it with its back-side against a heated metal surface. The material thus treated shows a considerable bronzing especially on the areas of high density.

When, however, 20 cm of a 1% alcoholic solution of the compound according to preparation 2 are added per kg. of emulsion, the result after mechanical drying is markedly better as can be seen from the following table:

Maximum density After Alter common mechanical drying drying Comparison material 1. 45 1. 28 Material according to the present inventio 1. 49 1. 43

wherein:

R is an aryl group,

R is an organic bivalent aliphatic group, and

X is a member selected from the group consisting of an oxygen atom and an NH group, and

X is a member selected from the group consisting of a hydrogen atom, an alkali metal atom, an ammonium group and a silver atom.

2. A photographic material comprising a support, at least one light-sensitive silver halide emulsion layer and at least one Water permeable layer on the same side of said support as said emulsion layer, wherein the lightsensitive silver halide emulsion layer and the water-permeable layer contain, as an antibronzing agent, an operable amount of-at least one compound of the formula:

R1' NH (I? X1 "R2SX2 wherein: R is an aryl group, R is an organic bivalent aliphaticgroup, and

- X is a member selected from the group consisting of an oxygen atom and an 'NH group, and

X is a member selected from the group consisting of a hydrogen atom, an alkali metal atom, an ammonium group anda silver atom. 3. A photographic material comprising a support, at

' least one light-sensitive silver halide emulsion layer and at least one water permeable layer on the same side of said support as said emulsion layer, wherein the Water-perme- 7 8 able layer contains, as an antibronzing agent, an operable 6. The photographic material of claim 1 wherein the amount of at least one compound of the formula: anti-bronzing agent has the formula:

wherein:

R is an aryl group,

R is an organic bivalent aliphatic group, and

X is a member selected from the group consisting of an 7. The photographic material of claim 1 wherein the anti-bronzing agent has the formula:

oxygen atom and an NI-I group, and 10 X is a member selected from the group consisting of a NH NH CHFSH hydrogen atom, an alkali metal atom, an ammonium 0 group and asilver atom. 8. The photographic material of claim 1 wherein the 4. The photographic material of claim 1 wherein the anti-bronzing agent h th form l anti-bronzing agent has the formula: 15

5. The photographic material of claim 1 wherein the anti-bronzing agent has the formula:

References Cited by the Examiner J. American Chemical Society 81, 1959, pp. 161-163. NHOO--CH2CH2SH H NORMAN G. TORCHIN, Primary Examiner.

A. D. RICCI, Assistant Examiner. 

1. A PHOTOGRAPHIC MATERIAL COMPRISING A SUPPORT AND AT LEAST ONE LIGHT-SENSITIVE SILVER HALIDE EMULSION LAYER, WHEREIN THE LIGHT-SENSITIVE SILVER HALIDE EMULSION LAYER, CONTAINS, AS AN ANTIBRONZING AGENT, AN OPERABLE AMOUNT OF AT LEAST ONE COMPOUND OF THE FORMULA: 